During the collapse of South Vietnam in 1975, President Gerald Ford ordered the evacuation of Vietnamese orphans from Saigon in the face of a massive North Vietnamese offensive. This mission, officially named Operation Babylift, began April 4, 1975, and evacuated more than 3,000 orphans throughout the month.

By mid-march more than 2,000 South Vietnamese refugees had been brought to the relative safety of Saigon on passenger jets donated by World Airways.

The first un-official Operation Babylift flight left Saigon without runway lights, a flight plan or formal clearance.

Babies are strapped into airplane seats enroute to LAX during "Operation Babylift" with airlifted orphans from Vietnam to the US. April 12, 1975.

South Vietnamese babies on a flight from Saigon to the USA (probably San Francisco) during Operation Babylift, the mass evacuation of children from South Vietnam at the end of the Vietnam War, from 3rd to 26th April 1975. (Photo by Jean-Claude FRANCOLON/Gamma-Rapho via Getty Images)

Orphans at the Ghenh Rang Orphanage in South Vietnam before Operation Babylift. Julie Davis, who lives in Minneapolis, believes that's her looking at the camera. (Courtesy of Julie Davis)

Frustrated by the lack of response from the US government, Ed Daly took matter into his own hands. Working with Friends of Children of Vietnam, he arranged to have 53 orphans and 22 adult attendants airlifted to the Presidio in San Francisco.

The news of Daly’s orphan rescue mission reached the White House.

It was reported that the World Airways DC-8 “took off without authority - no airport lights – no seats” and the babies “lay on the floor on blankets.” Neither the South Vietnamese nor U.S. governments had sanctioned Daly's flight; the US considered the cargo planes unsafe and unsuitable for the babies’ long flight.

Babies lined up on seats on a Pan American flight to Seattle. The healthier babies were in coach, sicker babies in first class and the most ill were in the VIP lounge area. (Courtesy of Joyce Wertz Harrington)

An American being evacuated from Vietnam tends to babies on the Pan American flight out of Saigon. The flight lasted 30 hours with multiple stops along the way. (Courtesy of Joyce Wertz Harrington)

Vietnamese children on the Pan American flight out of Saigon on April 5, 1975. “We had babies that were in seats, we had them in bassinets, under the seats, they were all but sticking out in the main aisle,” said Joyce Wertz Harrington, a volunteer. (Courtesy of Joyce Wertz Harrington)

Holding babies on the Pan American flight out of Saigon on April 5, 1975. The flight was among several that evacuated 2,547 children -- about 2,000 of those ended up in the U.S. (Courtesy of Joyce Wertz Harrington)

In Washington DC, an early morning memo was sent to Theodore Marrs, a Special Assistant to the President. In it, a recommendation was made to release funds to expedite the airlift of 2000 Vietnamese orphans to the US, where their adoptive families are anxiously waiting for them. The children were to be flown in safe planes to locations on the West Coast.

By noon, President Ford, at a televised press conference in San Diego California, announced that he had authorized the airlift, adding, “This is the least we can do, and we will do much, much more.”

An American volunteer carries a South Vietnamese infant from a Saigon orphanage. (Washington Times)

An aid worker lifts a child up for evacuation. (Sacramento Bee)

Ground crews loaded 250 small children and a staff of volunteers and nurses onto the first official Operation Babylift transport plane.

Shortly after takeoff, the locks on the rear cargo door of the C-5 failed, and the door blew off. The flight controls in the tail were also severely damaged.

The pilots attempted an emergency landing at Tan Son Nhut airbase, but the plane crashed in a marsh two miles short of the runway.

The impact crushed the cargo deck, where almost all of the orphans were kept. There were 138 people killed in the crash, including 78 children and 35 adults.

April 4, 1975. Crash site of Galaxy C5-A. The airplane departed from Saigon-Tan Son Nhut Airport, and crashed shortly after take-off. One hundred thiry-eight people were killed in the crash, including 78 children. (Photo: usmilitariaforum.com)

April 4, 1975. Crash site of Galaxy C5-A. The airplane departed from Saigon-Tan Son Nhut Airport, and crashed shortly after take-off. One hundred thiry-eight people were killed in the crash, including 78 children. (Courtesy of Bud Traynor )

April 4, 1975. The plane went down in a rice paddy just a couple miles from Saigon, killing 138 of the more than 300 on board. (Courtesy of Bud Traynor)

American military officials sift through the wreckage.

Two infant survivors are taken to hospital in Saigon.

Upon hearing about the tragedy Ford made this statement: “Our mission of mercy will continue. Other waiting orphans will make the journey. This tragedy must not deter us from offering new hope for the living. The government and people of the United States offer this hope in our rededication to assisting the Vietnamese orphans as best and as quickly as we can.”

President Ford and Mrs. Ford traveled to meet the orphans and their caregivers on the second flight, which arrived at San Francisco Airport.

Adoptive families were waiting for their children – including those families whose children had perished on the first flight. The list of fatalities had not been released, and parents did not know if their children were alive.

52 Vietnamese orphans arrive in a World Airways plane at Oakland Airport, April 2, 1975. (Photo: Jerry Telfer, The Chronicle)

Orphans aboard the first Operation Babylift flight at the end of the Vietnam War look out of the windows of a World Airways DC-8 jet as it flies them to the United States in April 1975. (AP)

Harmon Hall at San Francisco's Presidio is packed with mattresses, volunteers and Vietnamese orphans in Operation Babylift. Orphans flown to the United States from South Vietnam lived on the mattresses for four days as they were being processed for future adoption. (Photo: David Cupp / Denver Post Via Getty Images)

Strapped-in babies were being moved out of Vietnam at some of last moments. (Washington Times)

Among the anxious parent were Yul Brenner and his wife Jacquline, who were waiting for their adopted baby girl. Jaqueline said: "Yul and I are very concerned about our child… Like thousands of other Americans we are awaiting word of any kind." The Brenners contacted their friend Hugh Hefner, who used his private jet to bring 41 children to New York’s LaGuardia Airport on April 9, 1975.

An eye-witness, First Lady Betty Ford’s press secretary Sheila Weidenfeld, wrote: "I'll never forget the look on the face of one woman who was waiting nervously to find out [about her child]. She got good news, her child had arrived safely. She remained composed until she looked up and saw Mrs. Ford standing there and then something - a compassionate look from the First Lady? - made her crumble, and she began crying and crying."

April 2, 1975. World Airways flight attendants Carol Shabata (standing) and Valerie Witherspoon (kneeling) play with the Vietnamese orphans on the historic evacuation flight. (Courtesy: World Airways)

April 2, 1975. The East side of Hangar 110, Oakland International Airport as Members of the press and others meeting the first “un-official” flight of Vietnamese orphans. The bus seen in the picture was one of several that transported the arriving orphans to the Armory at the San Francisco Presidio. (Courtesy: World Airways)

April 2, 1975 Pat Palazzolo photographed the landing of Ed Daly’s unofficial “Babylift” flight – he heard the news of the plane’s arrival on the radio. (Photo: Pat Palazzolo)

April 2, 1975. Vietnamese orphans arrive at the California National Guard Armory on the Presidio. (Courtesy: YourDalyBread.com)

April 4, 1975. Interior views of first “Operation Babylift” flight. Volunteers held the babies and children in their laps during flight. (Photo: usmilitariaforum.com)

April 3, 1975. At a press conference in California, President Ford announces he is authorizing funds to speed the transfer of Vietnamese orphans to their adoptive U. S. families. (Gerald Ford Presidential Library A3900 – 15A)

April 4, 1975. Before the flight, the pilot allowed reporters to go through the cargo compartment and take pictures. The two Combat Photographers (MSgt Castro and Sgt Nance) were in this compartment for the flight and continued filming right until the end. (Photo: usmilitariaforum.com)

April 5, 1975. Medical checks were part of the arrival process for the babies and children upon arrival in the U.S. (Gerald Ford Presidential Library A3854-03A)

April 5, 1975. Some of the babies were treated for dehydration after landing in California. (Gerald Ford Presidential Library A3860-22A)

April 5, 1975. President and Mrs. Ford carrying Vietnamese children during “Operation Babylift.” The children’s adoptive parents were anxiously awaiting them at the airport. (Gerald Ford Presidential Library A3860-25A)

April 5, 1975. President Ford disembarks with a child in his arms. (Gerald Ford Presidential Library A3860-28A)

April 5, 1975. President Ford holds a Vietnamese baby in his lap before arriving at the airport hangar. (Gerald Ford Presidential Library A3860-35A)

Subsequent flights from Saigon were filled with babies, children and, as the North Vietnamese Army approached Saigon, adults.

On April 17, 1975 President Ford authorized the evacuation of thousands of "at risk" Vietnamese who were not American citizens.

At the evacuation’s height, from April 20 to 28, 1975, approximately 40 planes left Saigon every 24 hours. The aircraft was designed to transport no more than 100 passengers, but at times they carried in excess of 180 evacuees.

April 5, 1975. US Air Force personnel help children aboard the flight to their new home in the United States. (Photo: tavvntc.org)

April 1975. Hugh Hefner provided his plane the “Big Bunny” to transport Vietnamese children to New York City. Here, the babies are cared for by Playboy bunnies.

April 1975. Many of the employees deployed to the Defense Attaché Office Saigon helped escort evacuating Vietnamese orphans from Saigon during the collapse of South Vietnam in April 1975. (Photo: dia.mil)

April 1975. Military personnel attended to the children during the flights to their new home in the United States. Note the cardboard boxes being used as cribs for the infants. (Photo: dia.mil)

April 1975. Comforting a Vietnamese child during the flight to the U.S. (Photo: dia.mil)

April 1975. Nigel Brooks was working at Los Angeles Airport when these Vietnamese babies arrived. He noted that the babies were cradled inside the cardboard boxes during the flight. (Photo: Nigel Brooks)

April 1975. The Presidio was used as triage station – medical personnel and volunteers checked the babies and children for illness, fed them and kept them clean. (Photo: Golden Gate NRS, Park Archives, Letterman Army Hospital Photographic Slide Collection, GOGA 34782597)

On April 27, North Vietnamese forces were close enough to launch rockets into Saigon. Conditions in Saigon deteriorated on April 28, when North Vietnamese aircraft bombed the airport at Tan Son Nhut. The runways soon became swamped with aircraft and people, and by early morning on April 29, the use of fixed wing aircraft for evacuations ended. Civilians continued to be evacuated by helicopter to nearby military ships.

By the end of April, the Defense Attaché Office in Saigon had processed more than 40,000 evacuees, including the more than 3000 orphans from “Operation Babylift.”

A group of former Vietnamese orphans pose for photographs during ceremonies commemorating the 40th anniversary of Operation Babylift from Vietnam, April 24, 2015, in Holmdel, N.J. (Photo: Mel Evans/AP)